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Biomedical subjects

Franz J Frei

Publications and source records attributed to Franz J Frei.

6 recordsLinked to original sources
PubMed2006

Decrease of functional residual capacity and ventilation homogeneity after neuromuscular blockade in anesthetized young infants and preschool children.

BACKGROUND: Based on age-dependent differences in pulmonary mechanics, the effect of neuromuscular blockade may differ in infants compared with older children. The aim of this study was to determine the impact of neuromuscular blockade and its reversal by positive end-expiratory pressure (PEEP) on functional residual capacity (FRC) and ventilation distribution in young infants and preschool children. METHODS: The authors studied 14 infants (aged 0-6 months) and 25 preschool children (aged 2-6 yr). FRC and lung clearance index were calculated. Measurements were taken (1) after intubation, (2) during neuromuscular blockade, and (3) during neuromuscular blockade plus application of PEEP (3 cm H2O). RESULTS: Functional residual capacity (mean +/- SD) decreased from 21.3 +/- 4.7 ml/kg to 12.2 +/- 4.8 ml/kg (P < 0.001) during neuromuscular blockade in infants and from 25.6 +/- 5.9 ml/kg to 23.0 +/- 5.3 ml/kg (P < 0.001) in preschool children. With the application of PEEP, FRC increased to 22.3 +/- 5.9 ml/kg (P = 0.4829, compared with baseline) in infants and 28.2 +/- 5.8 ml/kg (P < 0.001) in children. The lung clearance index increased after neuromuscular blockade, whereas baseline values were regained after the application of PEEP. The changes induced by neuromuscular blockade were significantly greater in infants compared with preschool children (P < 0.001). CONCLUSIONS: Although the use of neuromuscular blockade decreased FRC and ventilation distribution substantially in both groups, the changes were more pronounced in young infants. With PEEP, FRC increased and ventilation homogeneity was restored. These results provide a rationale to use PEEP in anesthetized, paralyzed infants and children.

Anesthesia↗
PubMed2005

Respiratory reflex responses of the larynx differ between sevoflurane and propofol in pediatric patients.

BACKGROUND: The effects of anesthetics on airway protective reflexes have not been extensively characterized in children. The aim of this study was to compare the laryngeal reflex responses in children anesthetized with either sevoflurane or propofol under two levels of hypnosis using the Bispectral Index score (BIS). The authors hypothesized that the incidence of apnea with laryngospasm evoked by laryngeal stimulation would not differ between sevoflurane and propofol when used in equipotent doses and that laryngeal responsiveness would be diminished with increased levels of hypnosis. METHODS: Seventy children, aged 2-6 yr, scheduled to undergo elective surgery were randomly allocated to undergo propofol or sevoflurane anesthesia while breathing spontaneously through a laryngeal mask airway. Anesthesia was titrated to achieve the assigned level of hypnosis (BIS 40 +/- 5 or BIS 60 +/- 5) in random order. Laryngeal and respiratory responses were elicited by spraying distilled water on the laryngeal mucosa, and a blinded reviewer assessed evoked responses. RESULTS: Apnea with laryngospasm occurred more often during anesthesia with sevoflurane compared with propofol independent of the level of hypnosis: episodes lasting longer than 5 s, 34% versus 19% at BIS 40 and 34% versus 16% at BIS 60; episodes lasting longer than 10 s, 26% versus 10% at BIS 40 and 26% versus 6% at BIS 60 (group differences P < 0.04 and P < 0.01, respectively). In contrast, cough and expiration reflex occurred significantly more frequently in children anesthetized with propofol. CONCLUSION: Laryngeal and respiratory reflex responses in children aged 2-6 yr were different between sevoflurane and propofol independent of the levels of hypnosis examined in this study.

Anesthesia, Inhalation↗
PubMed2005

Improvement of motor-evoked potentials by ketamine and spatial facilitation during spinal surgery in a young child.

Monitoring motor evoked potentials is desirable during spine surgery but may be difficult to obtain in small children. In addition, the recording of reliable signals is often hampered by the presence of various anesthetics. We report the case of a young child whose motor evoked potentials were successfully monitored using a ketamine-based anesthesia and a newly introduced stimulation technique consisting of combined spatial and temporal facilitation.

Anesthesia, General↗
PubMed2003

The effects of common airway maneuvers on airway pressure and flow in children undergoing adenoidectomies.

UNLABELLED: Obstruction of the upper airway occurs frequently in anesthetized, spontaneously breathing children, especially in those with adenoidal hyperplasia. To improve airway patency, maneuvers such as chin lift (CL), jaw thrust (JT), and continuous positive airway pressure (CPAP) are often used. In this study, we examined the comparative efficacy of these maneuvers in children scheduled to undergo adenoidectomy. Sixteen children aged 2-9 yr were anesthetized with sevoflurane. During spontaneous breathing, the flows and pressures in the mask (ma), oropharynx (op), and esophagus (es) were measured simultaneously, and maximal pressure differences during inspiration (DeltaP) were calculated. After baseline recording, CL and JT maneuvers were performed in random order without and with CPAP (5 cm H(2)O). The observed DeltaP(ma) - P(es) of 12.3 +/- 3.4 cm H(2)O at baseline decreased with all airway maneuvers (P < 0.05). This resulted from decreases of DeltaP(ma) - P(op) (P < 0.05) and DeltaP(op) - P(es) (P < 0.05) in all interventions except CL, in which DeltaP(ma) - P(op) remained similar. In contrast, significant improvements of minute ventilation and maximal inspiratory peak flow (P > 0.05) were observed only with JT (with and without CPAP). We conclude that CL may improve airway patency and ventilation, whereas JT with or without CPAP was the most effective maneuver to overcome airway obstruction in children with adenoidal hyperplasia. IMPLICATIONS: Airway maneuvers are often used in anesthetized children to relieve airway obstruction during spontaneous ventilation. Compared with chin lift and continuous positive airway pressure, the jaw thrust maneuver was the most effective to improve airway patency and ventilation in children undergoing adenoidectomy.

Adenoidectomy↗
PubMed2002

Effect of continuous positive airway pressure on the measurement of thoracoabdominal asynchrony and minute ventilation in children anesthetized with sevoflurane and nitrous oxide.

STUDY OBJECTIVE: s: To quantify thoracoabdominal asynchrony (TAA) in children during anesthesia, and to measure the effect of continuous positive airway pressure (CPAP) on TAA, tidal volume (VT), and minute ventilation (E). DESIGN: Prospective, nonrandomized, controlled study. SETTING: Operating room of a university children's hospital. PARTICIPANTS: Ninety children aged 2 to 9 years scheduled for elective outpatient day surgery who were enrolled prospectively. METHODS: Each subject was anesthetized with sevoflurane 3% in equal parts O2 and N2O while breathing spontaneously through a facemask. Respiratory impedance plethysmography was used to calculate TAA indexes (phase angle [PA], phase relation in inspiration [PhRIB], phase relation in expiration, phase relation in total breath [PhRTB], and ratio of the inspiratory time to the total duration of the respiratory cycle [TI/TTOT]), VT, and E. Tidal gas flows were measured with a dual-hotwire anemometer with the sensor inserted between the facemask and the Y-piece of the anesthetic breathing circuit. This enabled the volume calibration of the respiratory impedance plethysmography equipment. The following conditions were compared: (1) no CPAP, (2) CPAP of 5 cm H2O, and (3) CPAP of 10 cm H2O. RESULTS: Eighty-one children completed the study protocol. All measurements of TAA with an inspiratory component (PA, PhRIB, PhRTB, and TI/TTOT) decreased significantly from baseline with the addition of CPAP to the circuit. Application of CPAP of 10 cm H2O decreased significantly mean VTs and Es compared with CPAP of 5 cm H2O and no CPAP. There were no differences in TAA for all conditions when comparing children scheduled for adenoidectomy with other surgical procedures. CONCLUSIONS: With spontaneously breathing anesthetized children, TAA decreases with the application of CPAP. CPAP of 5 cm H2O was as effective as CPAP of 10 cm H2O in reducing PA, PhRIB, PhRTB, and TI/TTOT. However, CPAP of 10 cm H2O also caused a significant decrease in VT and E.

Ambulatory Surgical Procedures↗